- "Life doesn't care about what you want. We don't get to choose."
- ―Teresa Mendoza
Teresa Mendoza is an exceptional survivor. A former money-changer from Sinaloa, she has risen to create and expand her own narcotics cartel, overseeing all cocaine transportation and distribution in Arizona and branching into Florida, Louisiana and Georgia.
Teresa was born in Culiacán and grew up in the Siete Gotas neighborhood, which she would later name her brand of tequila after. She was a salesgirl in the Buelna Mercado. She became a money changer at the age of fifteen, and by the age of sixteen she ran her own block2x01. She spent five years as a money changer on Calle Juarez1x02 before being picked up by Guero.
Her family was murdered by the cartels. Her mother was a nurse before she was born and used to say that "a bed is only as clean as its corners.2x01
She has long, wavy brown hair and is considered to be very pretty by all who meet her. Teresa has a scar hidden by her hair that she received after being punished by her boss for taking counterfeit bills while she was working in Sinaloa.
Teresa is often seen wearing shirts with three-quarter sleeves. She also keeps a necklace with the patron saint Malverde on it, but does not wear it.1x02
Teresa wears mainly white when she becomes the Queen as this color is supposed to protect her from her enemies.
Teresa is a survivor. She thinks quickly on her feet and does what it takes to make it out alive. Her alter ego, The Queen of the South, often appears to her and gives her advice when she is in dangerous situations, and she almost always follows it.
Teresa is resourceful and uses what is given to her, as proven when she uses any sort of weakness or distraction to her advantage. She is stubborn1x02 and wants to prove herself to Camila in order to keep herself safe. However, Teresa is also kind, as shown by the way that she deals with Tony, bandaging up Sandra's son,1x04 and by getting medicine for a girl with a fever.1x06 She fights for the people she loves, as evidenced by how far she goes to try to protect Tony and Brenda.
She doesn't want people to die when there's another way to do things -- like using the time she can see to get out of the cave.1x06 James thinks that this is impossible, but later joins her cartel hoping that it's true.3x02
She is hesitant to kill people, because that's not who she is. There are lines that she doesn't want to cross. She tries to save a man from being killed at Eric's party first by trying to free him then by flashing the headlights of James's car to try to distract Eric so that the man could escape. She is shaken by his death and calls Brenda telling her that she needs to get out of there.1x05
She doesn't like to do cocaine, refusing what is offered to her several times in the beginning. She also doesn't do coke with Leo, but is later forced to by La Capitana, and nearly overdoses.2x05 In Season 5 Teresa snorts cocaine to relieve stress.
She is good in numbers, observes more, talks less, can analyze a situation, and thinks fast. 
After Tony's death, Teresa understands that the only way to survive in this life is to be strong and ruthless. Teresa believes that if her operation becomes "too big to fail", she will be protected. Her goal is to become legit.
Teresa is good at math and can make calculations in her head. As she was a money changer in Sinaloa for five years, she can tell the difference between real and counterfeit money, which comes in handy when a customer tries to pay them in fake cash.1x03 She speaks both English and Spanish fluently and is very persuasive and can usually talk her way out of situations, making bold deals that leave both parties satisfied. Teresa talks less and listens more; she is reserved in her emotions, however she feels deeply for the people she cares about.
- Camila Vargas and Teresa have a rather tense relationship. In season 1, Camila protects Teresa because she believes that Teresa has something that Epifanio wants. Camila seems to like Teresa after Teresa proves her loyalty, first by swallowing the cocaine balloons that were prone to bursting,1x02 then by not revealing that she is tied to Camila when she is attacked.1x03 Camila says that she would have to kill Teresa if she tried to run and that she doesn't have to worry about Epifanio as 'this family' will protect her.1x05 Teresa promises her loyalty to Camila, but not her life.2x01 Camila teaches Teresa many things related to the business and plays a crucial part in the formation of the future Queen. After season 2 Camila is set on killing Teresa, because she blames her for the death of her husband.
- James Valdez: James and Teresa save each other's lives many times as they are often paired on missions for Camila. He advises her to not ingratiate herself with Camila, which will make it easier for her to get out of this life.1x03 Teresa falls in love with James slowly over seasons 1 and 2 and has a difficult time accepting it as she suffers the consequences of Guero's betrayal and is unable to trust. James is her forbidden and impossible love, on top of being her soulmate, mentor, friend and business partner. James helps Teresa find her place in the cartel world and become who she really is. Teresa dreams of James kissing her in season 2 despite the recent return of Guero. Teresa admits her feelings for James in season 3 when she tells Devon she is ready to die for him. By this time it is also clear James is in love with her as he risks his life for her multiple times and always comes back to her to help and support her. Devon's visit to the winery results in a very emotional exchange that brings them even closer together. They end up kissing and sleeping together. Their budding relationship takes a hit after Guero's death, however it gets back on track as they succeed in taking out the competition and their work proves that they are an excellent team. After Teresa, under Pote's influence, suspects James to be the mole that resulted in El Santo's death, James is hurt and tells Teresa that they need a break.3x11 Teresa recognizes her mistake and begs him to stay. James officially leaves in the season 3 finale in order to protect Teresa, unbeknownst to her. Teresa searches for James for six months after she expands her operation in New Orleans. Upon James's return and recovery from a gut shot wound, Teresa asks him to leave as she wants to protect him. She is afraid that once their relationship gets known, he may become a target like Guero and Tony. However, James finds a way to stay by her side and helps her expand her empire despite them not being together and despite his disappointment with the changes she has undergone and the greedy person she has become. Teresa and James have a very strong bond as they are soulmates before they are lovers. They find their way back to each other by the end of season 5. They plan their escape together and are successful in its execution. James is the person who has the most important influence on Teresa's journey and character development.
- Pote Galvez: Her relationship with him is complicated. Pote was present when Gato was raping her, and tried to tell Gato to stop, however did nothing else to prevent the rape. Pote owes Teresa his life for saving him when Epifanio turns on his men. Pote stays by her side as her most loyal sicario. Pote goes with her to Malta and they develop a closer relationship. When Pote's hand is mauled, he tells her that he might not be able to shoot, but he can still take a bullet for her. Teresa trusts Pote with her life and has her godson Tony live with him to protect him. After Tony learns that it was Pote that killed his father Chino, Teresa asks Tony to come live with her. Pote remains loyal by Teresa's side and prevents James from leaving in season 5. Pote ends up successfully escaping the biz with Kelly Anne and their daughter Lena after killing Boaz in a knife fight.
- Guero: Teresa was in a relationship with him for a year and they lived a relatively wealthy lifestyle as Guero was making good money as a pilot for the Vargas cartel. Guero is her first boyfriend who does not abuse her and Teresa genuinely loves him. Teresa is forced to run for her life when Guero is killed. Once Teresa realizes that Guero survived, stole from Epifanio, put her in danger and was the reason for her being raped and assaulted, she is devastated with his recklessness and she tells him their life cannot ever be under his terms. Teresa has made her choice, which is to grow in the biz, and tells him that he needs to make his. Guero helps Teresa establish a contact with a new supplier in Bolivia as well as capture Camila and Epifanio, which meeting results in Epifanio's death. Guero is killed when used as bait to get to Teresa in season 3.
- Brenda Parra: Her best friend, whom she loves and is protective of. They became friends after meeting through Guero. When Brenda first saw Teresa, she told her husband Chino to come look at her because she's so pretty.1x01
- Tony: Brenda's son, is her godson. She is shown to care for Tony and plays intermediary between them when they argue after Tony disappears for a few hours. After the death of Brenda, Teresa becomes responsible for the boy and promises him that she'll get them away from this life. She has him live with Pote during the first half of Season 4, up until he learns that Pote killed his father.
- Kelly Anne: Teresa and Kelly Anne become friends when Kelly Anne warns her of the plot Camila has set up against her. Teresa helps Kelly Anne escape after she murders her husband. Teresa has Kelly Anne take care of Tony and later allows her to join her operation in Phoenix. Kelly Anne uses drugs and after being wine boarded betrays Teresa. Teresa orders her execution, but when it becomes clear that she was spared, Teresa slowly forgives her and lets her back in her circle. Kelly Anne proves her loyalty and becomes the group's lawyer as well as Pote's love interest. She leaves the biz with Teresa and James at the end of the series.
- Boaz Jimenez: Teresa allows Boaz to join her organization and to manage Sinaloa and the corridor and later Miami in an attempt to forge relations and to keep him under control. She never trusts him due to his volatility and huge temper.
- Javier Jimenez: joins up with Teresa and James late in season 3. He helps recover King George and decides to stay with Teresa after James leaves. Javier makes serious mistakes in season 4 that jeopardize Teresa's business and these end up costing his life.
- King George: is fond of Teresa and they have a good partnership. Teresa goes to great lengths to recover him after he and Bilal are kidnapped by Cortez. Teresa sends him to Belize to set up an escape estate for all of them. Teresa trusts him explicitly with the details of her operation.
- Eddie Brucks is a jazz player and after James's disappearance in season 4, Teresa hooks up with Eddie for a short affair. After she is attacked in Nashville, Teresa breaks up with him as she realizes she puts his life in danger.
- Marcel Dumas: Teresa and Marcel meet in NOLA and go to war over a misunderstanding and several dead bodies on either side. Teresa manages to convince Dumas that their real adversary is Judge Lafayette and they become allies. In season 5 Teresa is forced to hand Dumas to the police for a crime he did not commit and although she gets him out of prison, he is not able to forgive her. Upon Teresa's exit, she leaves him the waterfront property and the funds to complete it as a sign of her true friendship.
- Judge Lafayette: Teresa learns the Judge owns NOLA very fast and that he is corrupt and mean. She tries to get under his skin many times, allows him to extort her and pays him a lot of money. She is never able to establish a good relationship due to a screw up by Javier of which she finds out too late. The Judge's plot against Teresa takes Tony as collateral damage and makes him an enemy for life. Teresa is working to expose the Judge's corruption when he is killed by Boaz.
- Oksana: Teresa and Oksana forge a friendship and a business partnership in seasons 4 and 5. They help each other in their dealings with Kostya.
- Devon Finch: Teresa meets him while working for Camila. He is impressed with her skills and attitude and later when she sets her own operation, and it is revealed that he works for the CIA, Devon backs Teresa's business as he believes it will grow to a level that the CIA can use it for its goals. Teresa knows that he and the CIA were behind El Santo's demise but is shocked to realize that Devon removed James so that their desire to do business in a better way and their feelings for each other do not slow her growth, when in season 5 he demands that they kill Kostya to end the war Boaz has started under his command.
Quotes from Teresa
- "You know driving like a pendejo's not gonna help, right?" - Teresa to James, in the car while he's driving erratically on the way to the airport.
- "Nothing wrong with beauty when there's brains beneath it." -Teresa to Camila.
- I'll fight until I die, but I'm not running anymore. - Teresa to Camila.
Quotes about Teresa
- "Shit, you got more guts than you could hang on a fence." -Sandra.
- "I've seen a lot of girls in my time who are trouble. And you... are trouble." - James Valdez.
- Brains, balls, and booty! If Rico Suave here didn't already have dibs, I might just make you my queen. - King George to Teresa about James.
- "Camila's lucky to have you. You one bad bitch." - Lil T, 2x10.
- In particularly tense situations, Teresa's heartbeat often becomes audible.
- She is moved to the pen where they keep the drug mules by James, after Camila tells him to get Teresa to trust him.1x03
- Camila gave her a $50,000 Rolex for noticing that the bills that Lopez was paying with were fake. Teresa didn't accept the gift, saying that she owed Camila that money anyway. Camila had James put it aside for her.1x03
- Her first solo mission for the Vargas Cartel (Texas) was a delivery to Sandra. She did not complete the other scheduled deliveries because Camila had someone else do them after what happened that day.1x04
- For the first half of season one, Teresa drives a beaten up red car, using a screwdriver for a key.
- Her grandmother taught her how to cook.1x04
- She used to own the same pair of shoes that Kim has in her closet, and she wears the shoes to Eric's party.1x05
- She believes in God.2x01
- Guero gave her the deed to his house as a birthday present,3x06 presenting a parallel to James trying to give her the keys to his compound and leaving.3x05
- Teresa says that her favorite memory is running around in the dahlia fields as a child.4x04